An asset protection system maintains a radio frequency field or signal in a monitored area. Assets have tags attached to them and are placed in the monitored area. The tags have a mechanism to attach them to the objects and have electronic components on board including a microprocessor, motion detector, radio frequency circuitry, audible alarm generator and in some cases, a passive EAS element. The tags are normally idle in the monitored area, but when the motion detector indicates that a tag is being moved, the RF circuitry checks for a signal or field at an expected frequency. If the tag does not detect a signal, the tag electronics determine that the tag has left the monitored area and generate an audible alarm. If a signal is detected, the tag returns to an idle state once it stops moving. The tags may also alarm if tampered with.